2-3. Operation of thermal shutdown

Figure 2.3 Operation of thermal shutdown

In the event of excessive power dissipation or the junction temperature exceeding a threshold due to an excessive increase in ambient temperature, the thermal shutdown (TSD) function turns off a load switch IC to protect itself and the system in which it is used.
Load switch ICs have a thermal shutdown temperature and a recovery temperature. The thermal shutdown temperature is the temperature at which TSD is tripped to turn off a load switch IC. When TSD is tripped, the resulting reduction in power dissipation causes its junction temperature to fall. Once it reaches a certain temperature, the load switch IC turns back on automatically. This temperature is the recovery temperature.
Unless the cause of the tripping of TSD is removed, the junction temperature rises back up, causing a load switch IC to enter the following loop: a turn-off of a load switch IC → a decrease in junction temperature → a turn-on of the load switch IC → an increase in junction temperature. The load switch IC should not be left at an excessive temperature for an extended period because doing so might affect the system stability or degrade the reliability of the load switch IC. Be sure to provide a fail-safe mechanism for a system in case of thermal shutdown.

The following link also provides a description of thermal shutdown:

Application note: Basics of Load Switch ICs

Chapter2 Convenient functions load switch ICs

2-1. Useful functions available with load switch ICs
2-2. Operation of overcurrent protection
2-4. Inrush current reducing
2-5. Auto discharge
2-6. Undervoltage lockout (UVLO)
2-7. Reverse-current protection

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